Method oe forming heater elements eor liquid-heaters



F. J. STUART.

METHOD'OF FORMING HEATER ELEMENTS FOR LIQUID HEATERS.

APPLICATlON FILED AUGLZZ, 1917.

Patented Nov. 18, 1919.

Swuemtoz 3: cf staarzi,

UNITED STATES PATENT OFFICE.

FRANK grosnrn stream, or ST. LOUIS, MISSOURI.

METHOD OF FORMING HEATER ELEMENTS FOR LIQUID-HEATERS.

To all whom it may concern:

Be' it known that I, FRANK J. STUART, a citizen of the United States,residing at St. Louis, State} of Missouri, ha-ve invented certain ,newand useful" Improvements in Methods of- Forming HeaterElements forLiquid Heaters, of which thefollowing is a specification.

This application includes matter divided from my copending' application,I filed *No vember "10, 1916, Serial Number 130,591, and to that 'eXtentis a" continuation of said earl er pplication,

The invention'has for an object to provide a suitable electrical heaterunit adapted to use in liquid heating apparatus. It is a particular aimof the invention togive an efficient and durable constni'ctionof heatingcoil, whereby the" complete" device may be produced at a very low cost.'To'this end, a special method of buildingupand form ng the heater coilhas been evolved, as-well'as-an especially desirable mountingfor such acoil by which it is adapted'to be introduced nto a receptacle or chamberin'which liquid 18 to be heated.

Additional objects, advantages, and features of invention will'appearfrom the-disclosure of one embodiment"oftheinvehtion as hereinafterdescribed-and shownin the drawings, wherein,--"' 'i Figure 1isanelevation of a coil asap.- plied to a heater for motor vehicle radators,-

Fig. 2 is a similar viewrof -the appliance, with a different mounting,

" Fig. 3 is a detail of the'mounting of the appliance, I

Fig.- 4 is a detail of the structure of the coil 1 Fig. 5is a detail'ofabushingelementf Fig. 6 is a detail ofa terminal connection and mountingfor the coil 'Figfi7 isa vertical sectional view of a modification ofthe appliance. I 1

There is illustrated in-dotted lines acylindrical heater casing 16,having large screw threads 17- throughout its length, this casing beingopen at its lower sideyand havingan integral annular 'fcr'own piece 18at the upper end," from which :thereextendsdownwardly a drain tube 19of-cylindrical form which may be located slightly eccentric to thecasing, and project a distance below the casing proper. The lower end ofthe casing is closed by a plate 20, ei'igaged slidably over theprojecting lower end of the tube 19, and held snugly against the end ofthe casing Specification of Letters Patent.

Patented Nov. 18, 1919.

Application filed August 22, 1917. Serial No. 187,708. 7

16 by means of a nut 21 secured on to the lower end of the tube 19.Fitted in the lower end of the tube there is an ordinary drain cock 22.Between the plate 20 and the casing a suitable heat insulating body 23may be disposed. Mounted upon the plate 20 there is a helical heatingcoil 24', having the lead wires 25 extended therefrom laterally throughopposite sides of the casing as indicated in Fig. 2, or extended downwardlythrough the plate as shown in Fig. 1. Theheatin'gcoil of Fig. 1.comprises a core element 26 of sufiicient rigidity to hold the coil inpropel-form and prevent undue distortion or damage thereto by vibrationduring the 'first stages of manufacture, and to aflord a good footing orbase for its mounting, the core in the present instance comprisingaheavy steel wire, around which a covering of suitable non-conducting andheatresisting material 27 such as asbestos is engaged, upon which inturn the heating coil proper is wound. The heating coil 33 stops shortof the endsof the wire 26 and its covering 27, and the ends of thesupport ing wire 26 and covering are bent into suitable eyes at 28, andsecured to the plate 20 by means of screws 29? The lead wires 30 areengaged in suitable bushings 31, where they are led in through thecasing or the plate 20, as the case may be, and in Fig. 5 there is showna form of bushing the inner part of which is longitudinally slitted in anumber of places circumferentiallyspaced, and the inner part of thebushing tapered and threaded, so that whenscrewed into the threadedopening in the plate 20the sides of the'bushin'g will be compressed soas to grip the wire 30 or its insulation, and hold it securely againstloose movement. The Wire 30 is connected to the end of the heatingcoil33 in any customary manner, within the casing.

In the production of the coil, suitable lengths of Wire 26 and itsacketing are pro vided, upon which the heating wire 33 is wound. Theends of the wire 33 being temporarily secured after winding, the heatingelement is then bent into the desired shape, as shown, for instance, at36 in Figs. 1 and 2. After being bent to this shape, the complete coilis then dipped in a paste of a suitable clay, cement, 'or othermaterial, of such consistency that when the surplus is shaken or drainedoff, a suitable coating is left upon the coil, this paste material beingof a suitable character to become hardened under the effect of heat, orotherwise, and being a non-conductor of electricity, but'of a characterto readily radiate and conduct heat. Potters clay has been used for thepurpose with satisfactory results. This has the effect of furtherstifl'ening and supporting the upper parts of the element.

In assembling the device, in the form shown in Fig. 1, the coil afterbeing dipped or otherwise coated with the stiffening insulation, isfirst mounted upon the insulating body 23 and the plate -20, the leadwires 30 then extended through the bushings in the plate 20, andconnected to the ends of the heating coil wire, after which the plate isadjusted in position on the bottom of the casing .16, and secured by thenut 21. The cook 22 may then be put in place and the device is'ready forattachment to the radiator. In the form shown in Fig. 1, the completecoil and its connections may be assembled on the plate 20, beforeintroduction into the casing 16, as will be readily apparent. The coil36 is formed with an upstanding portion 35 from the upper end of whichthe coil is continued downwardly, the part 35 being located closelywithin the coil 36at one side.

A further simple construction for the device which may be consideredpreferable is shown in Fig. *2, wherein there is shown a cylindricalcasing element 40. Within the element 40, a coil 44 is mounted, which inthe present instance need not have the central core wire 26 beforementioned if undesired, the coil being supported by means of a pin 45,driven through suitable diametrically alined openings in the upper partof the element 40, and engaging under one of the upper helices of thecoil 14. The ends of the resistance wire 46 of the coil are extendedthrough suitable openings at opposite sides of the tube, at its lowerend, in which bushings 47 may be fitted similar to the bushing 31, ifdesired. The wires 46 may be connected in any desired manner with anenergizing circuit as will be readily understood.

Various methods for mounting the'coil in a liquid container may beemployed,'in addition to those before described, and it may be foundpreferable to mount the coil upon its supportand 'make the connectionsbetween the heating coil and insulated binding posts before dipping theappliance, and then dipping the mounted coil so that its base portionand the terminal ends of the heating coil proper will all be covered bythe coating of outer insulating material, the subsequent hardening ofwhich will protect all parts of the device from contact with the liquidwhich may circulate about the coil. An example of this methodisillustrated in Fig. (3, wherein a coil is mounted upon a body 50,which may comprise the wall of a receptacle or a suitable base plateseparate therefrom, the terminal portion of the supporting element inthe coil being formed in the same manner as shown in Fig. l, and aspreviously described. The securing bolts 51, however, are insulated fromthe plate 0 in a suitable manner, and the terminal portions of the coreelement of the coil are also insulated therefrom by means of a sheet ofinsulating material The terminals of the heating wire are engaged underthe heads of the bolts 51, suitable washers 53 being disposed under theheads to clamp the insulating material around the stiffening wire of thecoil. After being secured in this way, either temporarily orpermanently, the coil is dipped so that the exterior coating ofinsulating material 54 will cover the bolt heads and the terminal endsof the heating wire, as well as the sheet 52 of insulating material. Thesheet may be of porcelain or indi'a rubber, as found most desirable.

The body 50 is formed with holes larger than the bolts 51, so that thelatter may not touch the body 50, and the bolts are held centered in theopenings byv means of simple bushings 55,.nuts 56 being engaged on theouter ends of the bolts to hold them in place, Binding nuts 5.7 may alsobe engaged upon the outer ends of the bolts for connecting suitablewires thereto.

If desired, the plate 50 may have a drain cock 58 fitted thereto asshown in Fig. 7, and be secured to the bottom of a casing 59 ofconsiderably larger diameter, having a small threaded nipple at theupper end adapted to be screwed into the usual small outlet opening of aradiator, in place of the usual drain cock.

\Vhat is claimed is:

The method of forming a heating coil or resistance element consisting inwinding upon a comparatively rigid wire jacketed with non-conductingmaterial, a suitable resistance wire to form a heating coil upon thesaid jacket, the winding stopping short of the end of said jacket andinclosed wire, then bending the assembly described into the shapefinally desired, and dipping the parts having said winding thereon in athin paste of a material adapted to harden by the ac- 'tion of heat orotherwise,.and which is a good conductor of heat;-

In testimony whereof I have affixed my signature in presence of twowitnesses.

FRANK Jos -PH STUART.

